On Music Video products, first enter a thumbnail image time in the top left image box to begin the thumbnail selection process.
After entering and saving a Thumbnail Time, Central will cut every frame within .5 seconds before and 1 second after the Thumbnail Time.
Click "Select Thumbnail" once it becomes available after saving a Thumbnail Time to see all of the frames in the short time range around the saved Thumbnail Time. When you have found the desired frame, click "Use As Video Thumbnail" on the image you want to use. You will then see the chosen frame displayed as the video thumbnail on your product.